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CNAS in the News
Evolution Can Occur in Less Than Ten Years
How fast can evolution take place? In just a few years, according to a new study on guppies led by UC Riverside's Swanne Gordon, graduate student in biology.
Swanne Gordon
Eight years later (less than 30 guppy generations), the researchers found that the guppies in the low-predation environment above the barrier waterfall had adapted to their new environment by producing larger and fewer offspring with each reproductive cycle. No such adaptation was seen in the guppies that colonized the high-predation environment below the barrier waterfall.
Guppies in the Damier River
"High-predation females invest more resources into current reproduction because a high rate of mortality, driven by predators, means these females may not get another chance to reproduce," explained Gordon, who works in the lab of David Reznick, professor of biology.
"Low-predation females, on the other hand, produce larger embryos because the larger babies are more competitive in the resource-limited environments typical of low-predation sites. Moreover, low-predation females produce fewer embryos not only because they have larger embryos but also because they invest fewer resources in current reproduction."
Study results appear in the July issue of The American Naturalist.
Natural guppy populations can be divided into two basic types. High-predation populations are usually found in the downstream reaches of rivers, where they coexist with predatory fishes that have strong effects on guppy demographics. Low-predation populations are typically found in upstream tributaries above barrier waterfalls, where strong predatory fishes are absent. Researchers have found that this broad contrast in predation regime has driven the evolution of many adaptive differences between the two guppy types in color, morphology, behavior, and life history.
David Reznick
Gordon's research team performed a second experiment to measure how well adapted to survival the new population of guppies were. To this end, they introduced two new sets of guppies, one from a portion of the Yarra River that contained predators and one from a predator-free tributary to the Yarra River into the high-and low-predation environments in the Damier River.
They found that the resident, locally adapted guppies were significantly more likely to survive a four-week time period than the guppies from the two sites on the Yarra River. This was especially true for juveniles. The adapted population of juveniles showed a 54-59 percent increase in survival rate compared to their counterparts from the newly introduced group.
Guppy predator Gobiomorus
"This shows that adaptive change can improve survival rates after fewer than ten years in a new environment," Gordon said. "It shows, too, that evolution might sometimes influence population dynamics in the face of environmental change."
She was joined in the study by Reznick and Michael Bryant of UCR; Michael Kinnison and Dylan Weese of the University of Maine, Orono; Katja Räsänen of the Swiss Federal Institute of Technology, Zurich, and the Swiss Federal Institute of Aquatic Science and Technology, Dübendorf; and Nathan Miller and Andrew Hendry of McGill University, Canada.
Financial support for the study was provided by the National Science Foundation, the Natural Sciences and Engineering Research Council of Canada, the Le Fonds Québécois de la Recherche sur la Nature et les Technologies, the Swedish Research Council, the Maine Agricultural and Forestry Experiment Station, and McGill University.
Entomologist receives honorary doctorate from ETH Zürich
Prof. Silvia Dorn, ETH, and Dr. Nancy Beckage, UCRNancy Beckage, professor of entomology and of cell biology and neuroscience, received an honorary Ph.D. degree from ETH (Swiss Federal Institute of Technology) Zürich in recognition of her achievements in the disciplines of insect endocrinology and insect immunology with impacts on agriculture. The ceremony was held on November 22, 2008.
Beckage's pioneering research in these disciplines has led to fundamental understanding of the interactions between pest insects and useful parasitoids, noted Prof. Silvia Dorn, former dean of ETH's Department of Agricultural and Food Sciences, in her introductory remarks.
"Professor Dr. Nancy Beckage of the University of California-Riverside [has] made a crucial contribution to our understanding of the importance of beneficial parasitoids as reliable antagonists of pest insects," she said. "In view of the global food shortage it is of high priority to know about the natural resources to safeguard yields and to exploit them. . . . Today Professor Beckage uses findings from this endocrinological research for an interdisciplinary research project in agricultural areas of West Africa."
After the ceremony, which was held on November 22, 2008, Beckage commented, "Given the internationally acclaimed reputation of ETH Zürich in science and technology I am indeed very honored to have been nominated and chosen by the faculty for this prestigious distinction."
ETH Zürich is, with Cambridge University and University College London, usually considered to have the best science graduate programs in Europe.
Rice geneticist honored by U.S. Department of Agriculture
Julia Bailey-Serres is lead recipient of the 2008 USDA National Research Initiative Discovery Award
For their landmark research leading to the development of flood-tolerant rice that can benefit farmers in flood-prone areas worldwide, Julia Bailey-Serres of UC Riverside, Pamela Ronald of UC Davis and David Mackill of the International Rice Research Institute in the Philippines were honored by the U.S. Department of Agriculture (USDA) with the 2008 USDA National Research Initiative Discovery Award.
The three scientists are, or have been, principal investigators on grants the USDA has awarded them for rice research. Their research achievements were celebrated at a ceremony at UC Riverside on Friday, Dec. 5.
Bailey-Serres, a professor of genetics in the Center for Plant Cell Biology and the Department of Botany and Plant Sciences, is the lead recipient of the USDA award. She has been the principal investigator on three USDA-funded projects that led to the Prof. Julia Bailey-Serresidentification and characterization of genes in rice that are responsible for flood tolerance. Two postdoctoral researchers, Kenong Xu (UC Davis) and Takeshi Fukao (UC Riverside), contributed largely to the research as well.
Gale A. Buchanan, the undersecretary for research education and economics at USDA, and Colien Hefferan, an administrator for the Cooperative State Research Education and Extension Service, presented the awards to Bailey-Serres and her colleagues.
Bailey-Serres and her collaborators have focused in particular on Sub1A, a gene responsible for flood tolerance and found only in some low-yielding rice varieties in India and Sri Lanka.
The characterization of the Sub1 trait in labs at UC Riverside and UC Davis has enabled researchers at the International Rice Research Institute to use sophisticated breeding technology to precisely transfer Sub1A into popular high-yielding rice varieties of countries in South and Southeast Asia, adding a much desired trait in these varieties: recovery after prolonged submergence.
The new rice varieties, which are already popular because of their pest- and disease-resistance and excellent grain quality, recently passed field tests in Bangladesh and India, and will be made available within two years to smallholder farmers in flood-prone areas in those countries.
"Prof. Bailey-Serres is the latest in a long line of eminent UC Riverside plant scientists," said Thomas O. Baldwin, the dean of UCR's College of Natural and Agricultural Sciences. "Since the beginnings of the university with the founding of the Citrus Experiment Station, what has distinguished our researchers is their rigorous knowledge of the very newest science coupled with a determination to use that science on everyday human problems."
The USDA funding of the Rice Sub1 Project began in the mid-1990s with two grants to Ronald and Mackill totaling nearly $490,000. Subsequently, three other USDA grants were awarded to Bailey-Serres, Ronald and Cynthia Larive, a professor of chemistry at UCR, bringing the grand total of USDA funding to the research team to nearly $1.45 million.
"The Sub1 project provides an excellent example of a productive research collaboration between a breeder and two molecular geneticists," Bailey-Serres said. "Each of the groups brought distinct expertise to the project.
"Dave Mackill recognized rice plants with exceptional submergence tolerance and sought the rice chromosome and region that carried the trait. Pamela Ronald had experience in fine mapping chromosome regions and hunting down genes using plant transformation technology. Takeshi Fukao and I provided expertise on flooding biology and gene regulation that led to the realization that the submergence tolerant trait includes a cluster of related genes."
For Bailey-Serres and Ronald, observing the robustness of the new submergence tolerant rice in farmers' fields in Bangladesh and India in November 2008 was an extraordinary experience. A farmer's wife told them she was very happy to see the new rice growing even though the plants had been underwater for 15 days.
"She and the other women of the family would not have to replant the field," Bailey-Serres said. "There would be rice now when otherwise there may have been none."
Renowned Biochemist to Lead UCR's College of Natural and Agricultural Sciences
Thomas O. Baldwin, a biochemist well known for his studies on protein folding, has been named the dean of the College of Natural and Agricultural Sciences (CNAS) at UC Riverside. His appointment is effective July 1.
"Dr. Baldwin brings to UCR a wealth of experience, exceptional leadership qualities and a distinguished background in teaching, scholarship and administration," said Acting Chancellor Robert Grey. "His scientific reputation and commitment to excellence make him an ideal choice to lead the College of Natural and Agricultural Sciences. I am delighted to welcome him to our campus."
Baldwin, 61, currently is head of the Department of Biochemistry & Molecular Biophysics at the University of Arizona, where he founded the Institute for Biomedical Science and Biotechnology, serving as its director from 2000 through 2003.
Research in his lab has exploited the bacterial bioluminescence system, the collection of genes that allow certain marine bacteria to emit light, as an experimental tool to study a variety of biological principles. He has investigated in detail the mechanism of the light-emitting reaction, as well as the process, called quorum sensing, that marine bacteria employ to express bioluminescence, a characteristic they express as a dense population of cells, but not as individual cells. Many non-bioluminescent bacteria use the same quorum sensing mechanism to coordinate other behaviors, such as pathogenesis, as a population of cells.
Baldwin is well known, too, for cloning of the bioluminescence genes from these bacteria and for transferring the bioluminescence characteristics into the common laboratory bacterium E. coli.
He is best known for his more recent work on "protein folding," the biochemical process, vitally important to all of life's processes, by which a protein assumes its three-dimensional structure. Protein misfolding leads to numerous disease states, including prion diseases such as "mad cow disease," Alzheimer's disease, Huntington's disease, and Parkinson's disease.
"As dean of the College of Natural and Agricultural Science, I hope to capitalize on the underlying strength of the faculty in the sciences to raise the profile of the college in the eyes of incoming students, making UCR a first choice university for students contemplating professions in basic and/or applied science," Baldwin said. "I'm looking forward to joining those at UCR and the community who are working to keep our young people in school and preparing them for college. I plan also to work closely with leaders in the business and industry communities of inland Southern California, seeking their counsel regarding workforce needs, targets of opportunity for research and development, and other areas of mutual interest."
His vision for the college is closely tied to the college's land-grant mission. "In a few years, the college will have dramatically increased its interplay with business and industry within inland Southern California and will be preparing even greater numbers of students for leadership roles in those industries, as well as the health professions and law," he said. "Research in the college, already recognized internationally for excellence in a number of fields, will be even more highly respected."
A native of Mississippi, Baldwin received his bachelor's degree in chemistry (1969) and his doctoral degree in zoology (1971), both from the University of Texas, Austin. He received postdoctoral training at Harvard University and began his academic career in biochemistry at the University of Illinois, Urbana, in 1975. In 1981, he moved to Texas A&M University, rising through the ranks to professor. He moved to the University of Arizona in 1999, where he is currently a professor of biochemistry and molecular biophysics.
At Texas A&M University, Baldwin formed the Center for Macromolecular Design, which he directed from 1991-1999. He has served nationally in the American Society for Biochemistry and Molecular Biology, the Protein Society and the Federation of American Societies for Experimental Biology in a variety of elected and appointed positions. He also has served on numerous committees and panels for the National Science Foundation and the National Institutes of Health.
The recipient of numerous awards for scholarship and research, including a Fulbright Scholarship and a Fogarty Senior International Fellowship, he was recognized as a Faculty Fellow for excellence in science and academic leadership by Texas A&M University and the Texas Agriculture Experiment Station.
With collaborators he has published more than 140 research papers. The editor or co-editor of four books, Baldwin also holds six patents based on his research. He has mentored more than 20 students who have received their doctoral degrees based on research done in his laboratory.
Baldwin will be joined by his wife, Miriam Ziegler, who is also a biochemist. They have two daughters: Rebecca, an attorney in Washington, D.C., and Ruth, a graduate student who lives with her husband in Berkeley, Calif.
Baldwin was selected from a national pool of nearly 50 candidates and will earn a base salary of $235,000 (additional details about his compensation will be made available soon at http://www.universityofcalifornia.edu/news/compensation/salaryactions.html). He will be the seventh CNAS dean, succeeding Steven Angle. Donald Cooksey, a professor of plant pathology and bacteriologist at UCR, has served as the college's interim dean since March 2007.
Under Cooksey's leadership, the strategic review of the CNAS structure that had begun under Dean Angle was completed. The resulting structural reorganization of the college into three academic divisions - agriculture and natural resources; life sciences; and physical and mathematical sciences - also has been completed during Cooksey's tenure.
Cooksey presided over the doubling of individual private support to the college. In addition, he enlarged the Chancellor's Agricultural Advisory Committee and extended its public outreach. He also collaborated with the Office of Research to set up a research grant program with Los Alamos National Laboratory, and supervised the redesign and updating of the CNAS Website as well as the creation of a quarterly college newsletter.
"I am pleased with the selection of Dr. Baldwin," Cooksey said. "He is already working hard to familiarize himself more with our programs and to develop several new programs to enhance our graduate education programs and development efforts."
The College of Natural and Agricultural Sciences, which brings together the areas of agricultural sciences, life sciences, physical sciences, and mathematical sciences into one academic unit, is internationally renowned for its research in pest and disease sciences, environmental sciences, conservation biology, genome biology, materials science, and nanotechnology.
Its history dates back to the establishment of the Citrus Experiment Station, which opened its doors on Feb. 14, 1907. The station moved to what is now the A. Gary Anderson School of Management in 1918, becoming the foundation for the UCR campus. In 1958, the College of Agriculture was formed. Steady growth, accompanied by a series of mergers with other science and mathematics disciplines, led, in 1974, to the College of Natural and Agricultural Sciences in its present form.
Martins-Green receives 2007-08 campus service award
Manuela Martins-Green, Professor of Cell Biology and Neuroscience, has
Been awarded a 2007-08 Distinguished Campus Service Award by the UCR Academic Senate.
An international expert in wound-healing, Martins-Green has a history of
extensive service and dedication to her department, the College of Natural
and Agricultural Sciences, and the Academic Senate.
As an assistant professor she helped generate National Science Foundation
funding for a new electron microscope and reorganized the biological
sciences departments on campus.
As an associate professor she served on numerous committees, including a
committee to reorganize the undergraduate program in biological sciences and
the Registration Fees Committee. She also chaired the Committee on
Committees.
Largely responsible for reinvigorating the practice of shared governance at
UCR, she moved decisively, on behalf of the faculty, to evaluate issues of
concern by the faculty in the merit and promotion process. She also
established mechanisms that helped invigorate and restore the atmosphere of
true shared governance between the faculty and the administration.
Martins-Green also played a prime role in reorganizing the Academic Senate
Office, more than doubling the staff and the budget. As chair of the
Academic Senate, she worked diligently on issues for the Child Care Center
on campus, revived a plan for a new Faculty Club, and established a
mentoring program for new women faculty (she has mentored one assistant
professor in the Bourns College of Engineering through tenure, and is
mentoring two assistant professors in the college at present).
She served on the search committee for a new chancellor at UCR, the search
committee for the director of the Health Sciences Research Institute, and
the Faculty Welfare Committee.
As chair of the Academic Senate, Martins-Green served on the state-wide
Academic Council. She also served on a senate-wide Committee on Civic
Engagement to evaluate ways to involve students in civic functions in their
regions.
Finally, she is on the committee to design and build the 10-campus School of
Global Health and well as on a committee charged with establishing a
Technology Institute in Tanzania.
Plants are critical to a sustainable future, says distinguished cell biologist
Natasha Raikhel, a distinguished professor of botany and plant sciences who received the honor of Faculty Research Lecturer for the 2007-08 academic year from the UCR Academic Senate Committee, gave the 56th Faculty Research Lecture on May 16.
Presented annually by the chancellor to only one campus individual, the Faculty Research Lecturer Award recognizes superior achievement in research and is the highest honor the Academic Senate bestows.
Raikhel's lecture was titled "Plant Biology: From Cells to Systems," and covered significant aspects of her laboratory work on the mechanistic understanding of cell wall biosynthesis and vacuolar biogenesis.
"A greater understanding of basic plant processes will allow us to predict responses of plants and ecosystems to our rapidly changing climate, leading to more efficient utilization, plant modifications and a more sustainable future," said Raikhel, who also holds the title of Ernst and Helen Leibacher Distinguished Professor of Plant Cell Biology. "Plants cannot live without cell walls and endomembrane systems, including vacuoles. These biological systems are important to humans in terms of health and well-being because they are the foundation for food, fiber and fuel production."
Raikhel's studies of the molecular mechanisms governing trafficking in plants and of genetic control of cell wall polysaccharide biosynthesis have made lasting scientific contributions in plant biology. Director of both the Institute for Integrative Genome Biology and the Center for Plant Cell Biology, and an internationally and nationally recognized leader in the plant cell biology field, she has pioneered the use of chemical genomics to advance knowledge of plant processes.
Her work has earned many distinguished awards, including a Guggenheim Fellowship, the Stephen Hales Prize from the American Society of Plant Biologists, and a Senior Fellowship of the Japan Society for Promotion of Science.
CNAS student wins NSF Fellowship
Matthew Wolak, a 1st-year Ph.D. student in Evolutionary Biology, has been awarded a prestigious National Science Foundation Fellowship, it was announced April 1 by the UCR Office of Undergraduate Scholarships, Fellowships, and Awards. Two other CNAS students, Benjamin Becerra, a 2nd-year Ph.D. student in Plant Biology, and Lynn Wihbey, a 2nd-year Ph.D. student in Plant Biology, received Honorable Mentions.
One other Fellowship and two Honorable Mentions were also awarded to UCR students, out of a total of 913 fellowship awards and 1,639 Honorable Mentions nationwide. Typically between 9,000 and 10,000 applications are received each year by NSF for the generous fellowship, which provides three years of funding —up to $121,500—for research-focused master's and PhD degrees in science, technology, engineering, and mathematics (STEM) fields.
"The Scholarship Office is pleased that our workshop last spring, when we hosted Tim Turner, the program director for the NSF Graduate Research Fellowship Program, appears to have resulted in quite a few UCR students being recognized this year," said Alice Chavez, coordinaotr of the office. "In the 2007 competition, we increased the volume of UCR applications by 70% over the previous year."
Research Team Led by UCR Entomologist Uses Tiny Wasp to Wipe Out Major Agricultural Pest in Tahiti
Biological control decimates glassy-winged sharpshooter populations in French Polynesian islands
A research team led by Mark Hoddle, a biological control specialist CNAS's Department of Entomology, has nearly eradicated the glassy-winged sharpshooter, a major agricultural pest, from the island of Tahiti and several other French Polynesian islands in the South Pacific Ocean. To achieve total pest suppression, the researchers used biological control, an inexpensive method that provides permanent control and can be applied to areas where the sharpshooter has become a nuisance. The method involves introducing Gonatocerus ashmeadi, a microscopic parasitic wasp, into an ecosystem under siege from the glassy-winged sharpshooter. The tiny stingless wasp attacks glassy-winged sharpshooter eggs by drilling a tiny hole in the egg through which the parasite lays its own egg. The wasp larva that hatches from the egg then eats the inside of the glassy-winged sharpshooter egg, killing it. The wasp larva completes its development inside the host egg and then emerges as a tiny winged parasite that searches for more glassy-winged sharpshooter eggs to kill.
"We had the technology to do the job cheaply and in a way that brought about permanent control of the glassy-winged sharpshooter in Tahiti and its neighboring islands," said Hoddle, an extension specialist and the director of the Center for Invasive Species Research. "When biological control — the use of a pest's natural enemies to keep the pest's population growth in check — works, it is very effective and safe in most cases. The parasites spread naturally and on their own, and they fly, requiring little, if any, continuous human assistance over a wide geographic area."
Study results appear in the February issue of Biological Invasions.
With no type of natural control in Tahiti, the excessive number of glassy-winged sharpshooters was a major social, economic, and agricultural nuisance on the island. The pest was especially present in high numbers in urban areas along the coast where it was severely affecting the health of trees and bushes upon which massive numbers of pests were feeding. When the island's government scientists approached Hoddle for guidance in 2003, he agreed to assist.
After safety evaluations, Hoddle and his colleagues released nearly 14,000 parasitic wasps at 27 sites in Tahiti between May 2005 and October 2005, resulting in rapid parasitism of glassy-winged sharpshooter eggs. By December 2005, the wasp had colonized the entire island of Tahiti, and glassy-winged sharpshooters decreased in number at all study sites to less than 5 percent of their original population density.
As a result of the rapid and dramatic reduction in the population of the glassy-winged sharpshooter in Tahiti, several problems associated with the pest diminished, such as excessive feeding on plants, high levels of sharpshooter excrement raining from trees, and home and shop invasions by hundreds of sharpshooters at night due to the pests' attraction to lights.
"Populations of the glassy-winged sharpshooter have been successfully maintained at a very low level in Tahiti for over two years, the time our experiments ended," Hoddle said. "Tahitian farmers have said their fruit production has improved in comparison to years when the sharpshooter was in abundance. The success of biological control with host-specific natural enemies demonstrates that alternative technologies that are not chemically driven can be very effective in suppressing invasive species."
Native to the southeastern U.S and northeastern Mexico, the sharpshooter is a half-inch long leaf hopper, dark brown in color, that has threatened the wine, table grape, and raisin industries in California since the 1980s because of a lethal bacteria that it spreads when feeding on plants.
The glassy-winged sharpshooter is a vector of Xylella fastidiosa, a bacterial pathogen that has potential to wipe out the grape, peach and almond industry, as well as many ornamental bushes and trees. Xylella fastidiosa causes Pierce's disease that can kill a grapevine in just two years.
Xylella kills plants by blocking the water conducting system, or xylem. The blockages reduce water flow to leaves. Water stress is visible as scorched leaves, which quickly dry and drop. Plants often die when these symptoms become obvious.
Because of its ability to spread a plant pathogen, the sharpshooter threatens native biodiversity and agriculture, In addition to grapes, the bacteria it spreads kills almonds, peaches, plums, olives, oleanders, and liquidambar.
A voracious eater, the sharpshooter can consume up to 100 times its body weight per day in plant fluids, and produces copious amounts of watery excreta that often "rains" down from trees, causing a social and recreational nuisance.
The glassy-winged sharpshooter, which invaded Tahiti in 1999, is also proving to be a nuisance in Easter Island (arrived 2005) and the Cook Islands (arrived 2007). It was also a pest in Hawai`i (arrived 2004) until G. ashmeadi, which controlled glassy-winged sharpshooters in Tahiti, accidentally arrived in Hawai`i.
Hoddle was joined in the study by Julie Grandgirard, Jerome N. Petit, George K. Roderick and Neil Davies of UC Berkeley. The French Polynesian government provided financial and logistical support for the project in French Polynesia.
Next in his research, Hoddle will work on a variety of pest species in their home countries to explore what controls their local populations.
"We are being proactive in our research by understanding these pests in their home environments," Hoddle said. "That way we will be better prepared for these new pests should they arrive unexpectedly one day at our doorstep."
Glassy-winged sharpshooters on leaves. (Image credits: Hoddle lab, UCR)
Glassy-winged sharpshooter.
Gonatocerus ashmeadi, a parasitic wasp.
Low Oxygen and Molybdenum Levels in Ancient Oceans Delayed Evolution of Life by Two Billion Years
Study tracked biogeochemical signatures preserved in ancient sedimentary rocks to establish nature and timing of oxygenation of Earth's atmosphere
(March 26, 2008)A deficiency of oxygen and the heavy metal molybdenum in the ancient deep ocean may have delayed the evolution of animal life on Earth by nearly two billion years, a study led by CNAS biogeochemists has found.
The researchers arrived at their result by tracking molybdenum in black shales, which are a kind of sedimentary rock rich in organic matter and usually found in the deep ocean. Molybdenum is a key micronutrient for life and serves as a proxy for oceanic and atmospheric oxygen amounts.
Study results appeared in the March 27 issue of Nature.
Following the initial rise of oxygen in the Earth's atmosphere 2.4 billion years ago, oxygen was transferred to the surface ocean to support oxygen-demanding microorganims. Yet the diversity of these single-celled life forms remained low, and their multicellular descendants, the animals, did not appear until about 600 million years ago, explained Timothy Lyons, a professor of biogeochemistry in the Department of Earth Sciences and one of the study's authors.
Suspecting that deficiencies in oxygen and molybdenum might explain this evolutionary lag, Lyons and his colleagues measured abundances of molybdenum in ancient marine sediments over time to estimate how much of the metal had been dissolved in the seawater in which the sediments formed.
The researchers found significant, firsthand evidence for a molybdenum-depleted ocean relative to the high levels measured in modern, oxygen-rich seawater.
"These molybdenum depletions may have retarded the development of complex life such as animals for almost two billion years of Earth history," Lyons said. "The amount of molybdenum in the ocean probably played a major role in the development of early life. As in the case of iron today, molybdenum can be thought of as a life-affirming micronutrient that regulates the biological cycling of nitrogen in the ocean.
"At the same time, molybdenum's low abundance in the early ocean tracks the global extent of oxygen-poor seawater and implies that the amount of oxygen in the atmosphere was still low.
"Knowing the amount of oxygen in the early ocean is important for many reasons, including a refined understanding of how and when appreciable oxygen first began to accumulate in the atmosphere," Lyons said. "These steps in oxygenation are what gave rise ultimately to the first animals almost 600 million years ago - just the last tenth or so of Earth history."
Earth's oxygenation
For animal life to commence, survive and eventually expand on Earth, a threshold amount of oxygen - estimated to be on the order of 1 to 10 percent of present atmospheric levels of oxygen - was needed.
Past research has shown that Earth's oxygenation occurred in two major steps:
The first step, around 2.4 billion years ago, took place as the ocean transitioned to a state where only the surface ocean was oxygenated by photosynthesizing bacteria, while the deep ocean was relatively oxygen-free.
The second step, around 600 million years ago, marked the occasion when the entire ocean became fully oxygenated through a process not yet fully understood.
"We wanted to know what the state of the ocean was between the two steps," said Clinton Scott, a graduate student working in Lyons's lab and the first author of the research paper. "By tracking molybdenum in shales rich in organic matter, we found the deep ocean remained oxygen- and molybdenum-deficient after the first step. This condition may have had a negative impact on the evolution of early eukaryotes, our single-celled ancestors. The molybdenum record also tells us that the deep ocean was already fully oxygenated by around 550 million years ago."
According to Scott, the timing of the oxygenation steps suggests that significant events in Earth history are related. Scientists have long speculated that the evolution of the first animals was linked somehow to the so-called Snowball Earth hypothesis, which posits that the Earth was covered from pole to pole in a thick sheet of ice for millions of years at a time. "The second oxygenation step took place not long after the last Snowball Earth episode ended around 600 million years ago," Scott said. "So one question is: Did this global glaciation play a role in the increasing abundance of oxygen which, in turn, enabled the evolution of animals?"
Scott and Lyons were joined in the research by A. Bekker of the Carnegie Institution of Washington, DC; Y. Shen of the Université du Québec à Montréal, Canada; S.W. Poulton of Newcastle University, Newcastle upon Tyne, United Kingdom; X. Chu of the Chinese Academy of Sciences, Beijing, China; and A.D. Anbar of Arizona State University, Tempe, Ariz.
The research was supported by grants from the U.S. National Science Foundation Division of Earth Sciences and the NASA Astrobiology Institute.
More about molybdenum as a proxy for ocean chemistry
Molybdenum, a metal abundant in the ocean today but less so at times in the past, is an excellent tracer of ancient chemistry for two reasons. First, the primary source of molybdenum to the ocean is oxidative weathering of continental crust, requiring oxygen in the atmosphere. Second, molybdenum is removed primarily in marine sediments where oxygen is absent and sulfide is abundant. Thus the enrichment of molybdenum in ancient organic-rich shales requires oxygen in the atmosphere but high sulfur and very low or no oxygen in the deep ocean. This combination is relatively rare today but may have been common when oxygen was less abundant in the earlier atmosphere.
When oxygen is available in the atmosphere, the amount of dissolved molybdenum in seawater is determined by the extent of hydrogen-sulfide-containing sediments and bottom waters (the colder, more isolated, lowermost layer of ocean water). Where sulfidic environments are widespread, the pool of molybdenum remaining in seawater is small, growing as the sulfidic environments shrink. The amount of molybdenum in the seawater is reflected in the magnitude of molybdenum enrichment in shales deposited in the deep ocean.
The UCR-led team of researchers estimated the size of the oceanic reservoir, and thus the extent of sulfidic bottom waters and sediments, based on the concentration of molybdenum in ancient black shales. They did so by dissolving the samples in a cocktail of acids and analyzing the dissolved rock for concentration using a mass spectrometer. The amount of this metal in the shales tracks the oxygen state of the early ocean and atmosphere and also points to the varying abundance of this essential ingredient of life. Molybdenum limitations may have delayed the development of eukaryotes, including the first animals, our earliest multicellular cousins.
CNAS Physicists to Coach High School Students on Mysteries of Particle Physics
Videoconference on campus to join San Jacinto High School students with peers in Portugal
(February 12, 2008)
Three UC Riverside particle physicists will participate in a physics "masterclass" on campus March 4-5 in which, through lectures and exercises, they first will introduce particle physics, experiments and detectors to students from a local high school, and then facilitate a videoconference between the students and a group of high school students in Portugal.
Particle physics, also called high-energy physics, is the area of science in which researchers study elementary particles - the most fundamental bits that constitute the universe - and the interactions between them.
The masterclass, an annual program of the European Particle Physics Outreach Group, is an interactive exercise in which high school students analyze specific particle physics data, receive coaching from expert particle physicists and their teacher, and work with peers far from home.
At UCR, 20 students from San Jacinto High School will work from noon to 4 p.m., March 4, with J. William Gary, Gail Hanson and Robert Clare, all professors in the Department of Physics and Astronomy. Gary will coordinate the students' visit and run exercises involving measurements on real data from particle physics experiments. Hanson will give a lecture to the visiting students on detection techniques and data reconstruction while Claire will lecture the students on the basics of particle physics.
The three physicists also will facilitate a videoconference - one of only two trans-Atlantic masterclass videoconferences this year - at 9 a.m., March 5. A camera, speakers, projector and screen will enable the San Jacinto High students to interact live and directly with the students in Portugal, who will have worked on similar particle physics problems. The two student groups will discuss, compare and consolidate their experimental results during the videoconference.
"We hope to excite the students about science, to give them a better understanding of how research works, and at the same time to teach them something fundamental about the natural world," said Gary, whose research involves the study of rare particle decays and searches for new forms of matter. "We hope to motivate the students to pursue their scientific studies when the enter college, either at UCR or elsewhere."
Besides giving high school students a greater understanding of and appreciation for experimental particle physics, the masterclass aims to educate them about the Large Hadron Collider, a powerful particle accelerator scheduled to begin operation this year at CERN, a particle physics laboratory in Switzerland. Gary, Hanson and Clare are members of the CMS (Compact Muon Solenoid) Collaboration, one of the two main experiments at the Large Hadron Collider.
Integrated Pest Management specialist wins state citrus award
Elizabeth Grafton-Cardwell, Extension Specialist in the Department of Entomology and Director of the Lindcove Research Center, received the Albert G. Salter Memorial Award on Jan. 18, 2008, from the California Citrus Quality Council "in recognition of her hard work, dedication, and vital contributions to the California citrus industry." For several decades, Dr. Grafton-Cardwell has provided timely research results to California citrus growers and pest control advisors on a wide range of insect and mite pest problems. She also plays a leadership role in extension education and information dissemination for citrus growers in California. Her many extension publications, informational brochures and seminars, field meetings, and her Citrus Entomology web site serve to update the industry on pest and natural enemy population dynamics, new monitoring and control methods, recently invasive pests, and important regulatory changes.
California Wildfire Conference Scheduled for March 4-5, 2008
Two-day meeting in Palm Desert will address fire preparation, impacts, recovery and outreach.
Damage to homes and businesses by wildfires can amount to hundreds of millions of dollars. Just in California, a region characterized by drought, hot weather and fierce Santa Ana winds, wildfire losses exceeded $60 million in 2006, destroying more than 430 structures.
In addition, nearly 560,000 acres of wildlands were burned in Southern California in 2007, destroying habitat for plants and animals and creating landslides that threatened urban and wildland habitats.
Now a two-day conference, organized by UC Riverside scientists, will focus on key aspects of California fires, such as preparing for fires, recovering from them and assessing their impact.
The 2008 Natural Resources Coordinating Conference, sponsored by the University of California Division of Agriculture and Natural Resources, is scheduled for March 4-5, 2008, at the UCR Palm Desert Graduate Center, Palm Desert, Calif. It is titled "Fires in California: Preparation, Impacts, Recovery, and Outreach."
"We have selected speakers to discuss a wide range of fire-related topics at the conference, including why some houses burn in a wildfire while others are spared; maintaining fuel breaks around structures; whether the practice of seeding burned areas is effective after a fire event; what some good, fire-safe landscaping practices might be; and ecological and environmental drivers of fire frequency," said Edith Allen, a professor of plant ecology and a cooperative extension research specialist in the Department of Botany and Plant Sciences who is organizing the conference along with Thomas Scott, a natural resource specialist at UCR. "The conference will also focus on how information on fires and fire safety can be effectively communicated to members of the public."
On March 5, the conference will offer a series of lectures from 8 a.m. to 5 p.m. on California fires. The lectures are grouped into three sessions: preparation for fire; fire impacts and recovery; and integrating fire issues through Cooperative Extension, the educational arm of the University of California.
